In the test I’m going to:
– use SpringRunner to start up the whole application with the full context
– Autowire Component that in production will be responsible for sending messages to WebSocket clients
– Build and configure Spring’s StompClient and connect a StompSession to my WebSocket server
– send a message over WebSocket and verify if my test client received it

Starting the application for tests

With SpringRunner.class used within jUnit test I start the app context and autowire the WSProxy component (the one that sends messages to WS clients):

The MyStompFrameHandler class is responsible for handling the incoming message in within the session and completing the CompletableFuture promise that it received as an argument. CompletableFuture is a helper variable needed to test asynchronous code: